The invention generally relates to communication connections for wired drill pipe joints.
A typical system for drilling an oil or gas well includes a tubular drill pipe, also called a “drill string,” and a drill bit that is located at the lower end of the pipe. During drilling, the drill bit is rotated to remove formation rock, and a drilling fluid called “mud” is circulated through the drill pipe and returns up the annul us for such purposes as removing thermal energy from the drill bit and removing debris that is generated by the drilling. A surface pumping system typically generates the circulating mud flow by delivering the mud to the central passageway of the drill pipe and receiving mud from the annulus of the well. More specifically, the circulating mud flow typically propagates downhole through the central passageway of the drill pipe, exits the drill pipe at nozzles that are located near the drill bit and returns to the surface pumping system via the annulus.
One technique to rotate the drill bit involves applying a rotational force (through a rotary table and kelly arrangement or through a motorized swivel, as examples) to the drill pipe at the surface of the well to rotate the drill bit at the bottom of the string. Another conventional technique to rotate the drill bit takes advantage of the mud flow through the drill pipe by using the flow to drive a downhole mud motor, which is located near the drill bit. The mud motor responds to the mud flow to produce a rotational force that turns the drill bit.
The drilling of the well may be aided by communication between the surface of the well and tools at the bottom of the drill pipe. In this regard, the bottom end of a conventional drill pipe may include tools that measure various downhole parameters (pressures, temperatures and formation parameters, as examples) and characteristics of the drilling (orientation of the drill hit, for example), which are communicated uphole. The uphole communication from a downhole location to the surface may involve the use of a mud pulse telemetry tool to modulate the circulating mud flow so that at the surface of the well, the modulated mud flow may be decoded to extract data relating to downhole measurements. Additionally, downhole communication may be established from the surface of the well to downhole tools of the drill pipe through one of a number of different conventional telemetry techniques. This downhole communication may involve, as examples, acoustic or electromagnetic signaling.
A more recent innovation in drill pipe telemetry involves the use of a wired drill pipe (WDP) infrastructure, such as the WDP infrastructure that is described in U.S. Patent Application Publication No. US 2006/0225926 A1, entitled, “METHOD AND CONDUIT FOR TRANSMITTING SIGNALS,” which published on Oct. 12, 2006 and is owned by the same assignee as the present application. The WDP infrastructure typically includes communication lines that are embedded in the housing of the drill pipe. Because a conventional drill pipe may be formed from jointed tubing sections, communication connections for the WDP infrastructure may be made at each joint of the drill string. Although any one communication connection may be used for bidirectional communications, providing separate communication connections dedicated to either uphole or downhole communications may facilitate the transmission of information. Furthermore, multiple connections used for communication in a given direction may provide additional advantages such as transmitting in a differential mode, which can allow rejection of common mode noise, and balanced transmission. Or the multiple connections can provide additional communication channels in either direction. In addition, in some applications, power signals are communicated to the downhole fool in addition to data and/or control signals. In such an application, it would be desirable to employ a separate communication path for the power signals such that noise generated on the power communication path does not interfere with data and control signals.